Melting-Points and Possible Sintering Temperatures of Metals

The first reports on the incorporation of molybdenum disulphide in a metal matrix were those mentioned previously which were published by Bowden in 1950. He reported a coefficient of friction of 0.13 for a composite in sintered copper. In his other metallic composite the molybdenum disulphide was formed in situ by hydrogen sulphide in sintered molybdenum and had a coefficient of friction of 0.06. At about the same time R L Johnson et al at NACA studied the effect of molybdenum disulphide concentration in silver with 5% of copper. They reported coefficients of friction as low as 0.17 and found that the friction decreased with increasing concentration of molybdenum disulphide. Their wear rates were high, around 10 mm /Nm, but this work was the fore-runner of many studies using the same components. 

Powder metallurgy techniques have been used to produce a very wide range of compacts containing molybdenum disulphide in such metals as mixed iron-palladium, iron-platinum , tantalum , iron-tantalum , molybdenum-tantalum , and molybdenum-niobium . The concentration of molybdenum disulphide in these compacts has risen to 90% compared with less than 35% in earlier materials. Composites containing nickel were found to be unsatisfactory because of high friction and wear. 

Campbell and Van Wyk hot-pressed their iron-palladium and iron-platinum composites at 1090°C (2000°F) and 50MPa. They prepared a variety of composites containing nickel in a similar manner, but none of these was successful. They used graphite dies, and considered that this helped to create a reducing environment during the hot-pressing, which prevented oxidation of the molybdenum disulphide. Hubbell 

Studied some of the same materials as Hubbell et al values. 

Martin and Murphy ° compared twenty-five different solid lubricant composites for use in small arms. The best performance was obtained with a composite of molybdenum disulphide in molybdenum with niobium and copper. This had a lower wear rate (0.224 x 10 mm /Nm) and lower coefficient of friction (0.05 - 0.15) than any of the twenty-one polymer-based composites. 

---

Table 12.9 Melting-Points and Possible Sintering Temperatures of Metals...

---